The Era of Engraved Stone

Levi, a doctor of geology, traveled to the Ice Age and Stone Age. The first thing he saw when he opened his eyes was an obsidian spear pressed against his throat. But he discovered that the land beneath his feet contained saltpeter, iron ore, copper and tin—the earth wrote a map of an entire civilization for him. He taught the tribe to make fire, smelt iron, build walls, and make salt, transforming himself from a "captive" to an "enlightened". But in the snowy plains to the west, another time traveler - the special forces who believe in iron-blooded rule - has twisted the scattered tribes into a knife. One builds a wall with knowledge, and the other holds a sword with blood and iron. Two modern people who fell from the same extraterrestrial scar will eventually decide the direction of civilization in this wilderness.